Abstract: This invention provides an oil-cooled motor, the housing of the motor comprising an oil storage chamber and at least one passage communicating with the storage chamber. The storage chamber is connected with one end of the armature shaft of the motor, while the passageway meets the other end of the armature shaft. Also, the armature shaft is provided with an axial passage communicating with the storage chamber and the passageway in the housing, whereby, during operation of the motor, the cooling oil will circulate along said passage and passageway and thus maintain the motor at a reduced operating temperature level. In another embodiment according to this invention, the housing of the motor is further provided with a second storage chamber around gearing at the output end of the armature shaft, and the oil stored in the second chamber is in communication with the passageway provided in the housing and the passage in the armature shaft. With this arrangement, better cooling effect may be obtained.